Tesla Coil

[5614]

Tesla coils often enter conversations but so far [i searched for it anyway] i cant see an official tesla coil thread.

 

so i though't i'd start one.... people can learn about making them... post pictures of currently made and working ones and so on and so forth.

 

i was thinking of making one [my first one] and was wondering for some pictures of others and just general advice and stuff!

[pulkit]

Not so sure what a Tesla coil is. Is it a metallic loop in which no magnetic field may exsist ? I mean is it like a magnetic analogue of a Faraday cage ?

[Lance]

I just want to start by saying that despite all the warnings for beginners tesla coiling is a great hobby. Don’t let people discourage you will warnings about horrible deaths and going into debt.

 

Next I would like to say how incredibly dangerous tesla coiling is and the huge expense of building one. Before building one do as much research as possible and plan everything out. If you don’t plan everything out you WILL end up with parts that don’t work (such as capacitors, transformers, heart, lungs, ECT.) Also I will NOT be held responsible if you do die a horrible death.

 

There is another tesla coil thread here.

 

Be sure to go to http://web.tampabay.rr.com/swilson9/teslamap.html and download tesla map.

 

You should also think about where you plan on building/testing your tesla coil. It’s hard to do it outside because of the brightness of the sun and the complaining or your neighbors. It’s hard to do this inside because of a decent ground and the malfunctioning of your computer. I do it in the lab in my basement and I use the cold water pipe for my ground. Just a though.

 

Not so sure what a Tesla coil is. Is it a metallic loop in which no magnetic field may exsist ? I mean is it like a magnetic analogue of a Faraday cage ?

 

A tesla coil is an air core resonant transformer. They are using for generating huge voltages.

[Tritium]

I recommend testing your Tesla coil outside because it can produce ozone and nitrogen oxides. These gases not only smell horrible but they can also corrode your lung tissue. You also want to make sure you discharge your capacitor every time you use it. When working with something this dangerous you need to learn all you can before you build one.

[Lance]

I dont know, I kind of like the way ozone smells.

[drz]

What is the difference between a tesla coil and a typical automotive ignition coil? I even notice on one of my Z cars the coild has "TESLA" printed on the outside.

 

My reasoning for this question is, if tesla coils are essentially the same thing, why not just go spend $20 bucks and get a coil from the parts store?

[Lance]

An ignition coil has a ferrite core. Although I *think* its just a rod. I have heard of people removing the rod and runing them as solid state telsa coils but you cant get very far because the insulation will break down.

[Tritium]

Does ozone have a sweet smell or was that some other gas? It smelled like candy

[5614]

imported from:

http://www.scienceforums.net/forums/showthread.php?t=4571

and posted by lance, thanks lance!

 

Well nearly every part of my coil is temporary because of my lack of money. Not only that but the capacitor bank I used which was already too small is now 40% dead. My max spark length is 14" while it should be more than 24" with my power supply. I bought the wrong type of magnet wire so my secondary is to skinny and short.

 

Other than that' date=' I’m happy with it.

 

 

Despite what people say, tesla coils can be made with just about anything. (Mine is a good example.)

 

Basically you have a power supply, capacitor bank, spark gap, primary, and secondary. The power supply charges the caps, breaks down the spark gaps and drains the caps through the primary inducing a charge in the secondary. Because the bottom of the secondary is grounded it acts like a cap to the ground. The toroid increases capacitance to the ground.

 

[u']Power supply [/u]

So first just find a power supply. If you live in a city there is probably a neon sign shop around. They will normally give you a free neon sign transformer (NST) that is damaged. Try to get one that is rated at 12kv or 15kv. You can also buy one on ebay for about $20 and another $20 for shipping (they are heavy).

 

Secondary

Then find some PVC pipe and magnet wire, 4" dia. is the best for the PVC. The magnet wire can be just about any size from 22AWG to 28AWG. Just wrap the wire around the PVC tell you have 800-1400 turns. You will need a few pounds of the magnet wire so ebay is your best bet. After you wind it just spray on a few coats of polyurethane varnish to make in nice and shiny.

 

Primary

The primary can be just about anything as long as it has about 15-20 turns. Most people use copper refrigerator pipe from a hardware store. It is normally wound flat on a board. I made one like that but it only had 8 turns which was not enough so I just wound some high voltage wire vertically on a plastic container that had Chinese soup in it. It’s only temporary but it works.

 

Spark gap

Anything! Two nails sticking out of a board would work. Although it’s best to use more than one segment so it stays cool. You could also vacuum the spark gap. I get MUCH better performance with a vacuum on my single gap.

 

Capacitor bank

Ah, now for the hard part. After you build everything else download teslamap . Then just input all your specs and it will tell you the resonant cap size. You should try to make your bank that size for best performance but it’s not a requirement. Also remember that your caps have to survive the PEAK voltage of your transformer. A 15KV NST will have a peak of 21KV; it would also be a good idea to have the bank rated much higher. 30KV would be nice. You can build "saltwater caps" with clear beer bottles and saltwater or you can buy a large pulse rated cap or you can build a multi mini capacitor bank (MMC). I would suggest The MMC because it can be altered very easily. Your best bet would be here. Tesla map has a built in capacitor calculator so you know exactly how many caps in series and parallel you would need.

 

Toroid

Your toroid can be just about anything too. I prefer aluminum ducting in a donut shape on top of the secondary. Wielding two metal bowls together would probably work too.

 

Tuning

After you put everything together you have to tune it to get the maximum spark length. Basically you just play with all the parts. The primary has to be "taped" in different areas. The position of the toroid also makes a difference along with the distance of the spark gap. Just move everything around and turn it on and off seeing as to what makes a difference.

 

WARNING

Every part of a tesla coil circuit can be lethal! You MUST have bleed resistors across EVERY capacitor. Also the secondary of the tesla coil can build up a static charge whish is not directly dangerous unless you freak out and fall on something sharp.

 

Note my Signature:D

__________________

"The first time I powered this thing up I was pretty sure I would die... So I was extra cautious." -Afrotech

once again, we all stress the dangers of this and all of that other legal stuff we have to say in case you try to sue me or lance for teaching you dangerous stuff!

[Lance]

Does ozone have a sweet smell or was that some other gas? It smelled like candy

 

Yea, it’s a very distinctive smell. It’s impossible to mistake for anything else.

[Pangloss]

I'm confused... why would you want to build one of these things?

[Lance]

I'm confused... why would you want to build one of these things?

 

That's the one question I get asked the most, and yet I still have not come up with a decent answer.

 

Why not? Why do any of the experiments shown in this forum? Why do people collect stamps and build model airplanes? Why do artists paint and photographers take pictures? Why do people jump off cliffs with an elastic cord tied to there feet? Beats me.

[Dave]

I'm confused... why would you want to build one of these things?

 

Makes a cool thing to show to people, and you can say "heh, I built a tesla coil!" to people. Apart from that, I can't really see any other use.

[Pangloss]

That's as good an answer as any. (grin)

 

Wikipedia has a good article on the subject:

http://en.wikipedia.org/wiki/Tesla_coil

[YT2095]

actualy non of my coils were at all what I`de call "Expensive"?

 

other than the copper tubing 1/4 inch x 25 foot (cost 7 quid from a plumbers merchant) and the 2 Balti Woks I soldered together to make the "toroid/dome" 99 pence each, the rest all came from scrap materials

 

 

he`s right about needing a good Earth strap though!

[Dave]

and the 2 Balti Woks I soldered together to make the "toroid/dome"

 

That cracks me up every time

[Lance]

actualy non of my coils were at all what I`de call "Expensive"?

 

other than the copper tubing 1/4 inch x 25 foot (cost 7 quid from a plumbers merchant) and the 2 Balti Woks I soldered together to make the "toroid/dome" 99 pence each' date=' the rest all came from scrap materials

[/quote']

 

Well I think it depends on how experienced you are. The parts for my coil were never good enough for me so I kept on ordering new ones. I also had parts that just weren’t up for the job. I’m on my third capacitor bank, I’m getting ready to rebuild a third primary, I have had three secondarys, two different toroids... I had to buy the NST off of ebay (high shipping), magnet wire is not cheap.

 

If you live in a large city you can probably get the NST for free. Maybe I’m just a perfectionist and an exception. Although I’m thinking of building a smaller coil with he parts that didn’t work so well for my larger coil. I already have all the parts for it besides the power supply.

 

If I truly knew what I was doing when I started (like you did) I think it would have been cheaper.

[5614]

people always talk about 'smaller' and 'bigger' ones, but what is generally classified as a smaller one and what as a big one? im talking voltages... spark distances etc

[Lance]

people always talk about 'smaller' and 'bigger' ones, but what is generally classified as a smaller one and what as a big one? im talking voltages... spark distances etc

 

Well.... I don’t think I have ever really seen the sizes defined. I think the big/small is based on the power of the power supply. I would say 100-300W=small 300-600W=Medium and more than that Large. But that’s just an opinion. I’m sure everybody would define it differently. You could also define size as based on caps and the diameter of your secondary.

 

It’s really impossible to say the arc length based on the power supply alone and I don’t really have enough experience to say anyway.

[5614]

yeah, i just wanted a rough opinion on the measurements of power, thanks!

 

[from another thread:]

Yes, but the small ones are only for small signs and are solid-state/ high frequency. They wont work for a tesla coil.

 

so when buying a neon sign, with the intention of using the transformer for a tesla coil, how do you know which neon sign to buy?

[Lance]

Well first of all it pretty easy to tell the difference between the normal transformers and solid-state. The Normal ones will weigh about 15-30lb for a 12-30 transformer. They will also be in a grounded metal case filled with tar or some other heavy insulator. You can also look at the label, generally they will say what frequency they run at.

 

 

Good

bad!!!!

[5614]

ok, coz i was thinking of buying an actual neon sign, then i could nick the transformer and still have the neon lights [for lighting or maybe just for the gas itself, which is quite unreactive so i dunno why i'd want it but anyway] so i was wondering if you buy a whole neon sign, normally the transformers on the back look like you 'bad' example, so would i have to find another neon light, do the neon signs generally come with the 'good' transformers, or do you buy them seperately?

[Lance]

Well the 'good' transformers are for much larger signs.

 

I think 12-30 transformers are rated for 45' of 15mm neon tubing.

[jgerlica]

For excellent information on design: BLAH!!!!!

For performance questions go here: BLAH AGAIN!!!!

[5614]

woa jgerlica, that site is wicked, thanks loads

 

from the above mentioned site, seeing as were talk about spark lengths ealier, if you insert your input power [Watts] then this site will give you an estimate of the spark length:

http://www.deepfriedneon.com/tesla_frame6.html